Common Internet access methods include the use of cable modems or Digital Subscriber Line (DSL). These access methods have a limited amount of upstream bandwidth to accommodate the flow of data to the Internet. However, applications such as Voice over IP (VoIP) will malfunction unless a certain amount of upstream bandwidth is reserved or guaranteed. For example, effective communication through VoIP generally requires a delay of no greater than 100 to 150 milliseconds. The limited upstream bandwidth provided by conventional Internet access methods such as DSL or cable modems is a factor in this delay. If too little upstream data rate is available, the voice data rate is slowed such that the acceptable delay limit will be violated. For example, VoIP implemented with a G.711 codec may require up to 100 kbps in upstream data rate. But note that a VoIP caller may also be emailing others while speaking. In addition, other users of a network serviced by the Internet access method may also be sending data to the Internet. Thus, the network may implement some form of Quality of Service (QoS) to appropriately prioritize data packets. To implement QoS intelligently, a measure of the upstream bandwidth is usually necessary. For example, if the upstream bandwidth is ample enough to accommodate all the upstream data traffic, there would be no need to restrict the transmission of lower-priority data packets. Conversely, if the upstream bandwidth is particularly limited, the transmission of lower-priority data packets may need to be restricted. For example, it is common for a configuration page for a home router to simply ask the user what is the upstream bandwidth. Because cable or DSL modems are generally transparent to the router, a typical user has no intelligent way of assessing the upstream bandwidth. Some network devices such as routers calculate the upstream bandwidth by sending data to a server on the Internet. The upstream data rate (and hence bandwidth) may then be calculated by measuring the time necessary to upload the data to the server. But such a server must be maintained for this purpose and the measurement time taken is the entire transmission time to the server, not just the upstream rate of the Internet access method.
Accordingly, there is a need in the art for improved upstream bandwidth estimation techniques.